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17th International Conference on World Wide Web 2008, WWW'08

作者： Di, Nan Yao, Conglei Duan, Mengcheng Zhu, Jonathan J.H. Li, Xiaoming Dept. of Computer Science and Technology Peking University Beijing 100871 China Dept. of Media and Communication City University of Hong Kong Kowloon Hong Kong State Key Laboratory of Advanced Optical Communication Systems and Networks Peking University Beijing 100871 China

ISBN: (纸本)9781605580852

As opposed to representing a document as a "bag of words" in most information retrieval applications, we propose a model of representing a web page as sets of named entities of multiple types. Specifically, four types of named entities are extracted, namely person, geographic location, organization, and time. Moreover, the relations among these entities are also extracted, weighted, classified and marked by labels. On top of this model, some interesting applications are demonstrated. In particular, we introduce a notion of person-activity, which contains four different elements: person, location, time and activity. With this notion and based on a reasonably large set of web pages, we are able to show how one person's activities can be attributed by time and location, which gives a good idea of the mobility of the person under question.

关键词： Websites

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相干态光源含噪声情况下连续变量量子密钥分发的安全性分析

相干态光源含噪声情况下连续变量量子密钥分发的安全性分析

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中国电子学会第十五届青年学术年会

作者： Yang Jian 杨健 Shen Yong 沈咏 Zhou Changjie 周昌杰 Guo Hong 郭弘 CREAM Group State Key Laboratory of Advanced Optical Communication Systems and Networks and Institu 北京大学信息科学技术学院量子电子学研究所区域光纤通信网与新型光通信系统国家重点实验室CREAM小组北京100871

We analyze the security of the CV-QKD protocol with noisy coherent states，which is assumed to be induced a neutral party，*** the model, we prove the equivalence between the prepare and measurement (P&M) scheme a... 详细信息

关键词：通信安全密钥管理相干态光源噪声控制

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Design and analysis of a multicast-capable optical cross-connect

Design and analysis of a multicast-capable optical cross-con...

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optical Transmission, Switching, and Subsystems VI

作者： Zhang, Chunlei Hu, Weisheng School of Electronic and Information Engineering Lanzhou Jiaotong University 88 West Anning Road Lanzhou Gansu 730070 China State Key Lab. of Advanced Optical Communication System and Networks Shanghai Jiaotong University 800 Dongchuan Road shanghai 200240 China

As multicast applications become more and more popular, implementing multicast in optical domain has attracted more and more attention due to its more efficient bandwidth usage. The MC-OXC is the key for realizing multicasting at optical layer and directly affects the performance of the multicast services in WDM networks. In this paper, a novel mixed-integrated optical multicast switch for multicast-capable cross-connect is proposed. The new architecture uses power splitters for multicast connections only, allowing unicast sessions to pass without enduring unnecessary power loss. And also the performances of the MC-OXC are analyzed. We performed the cost and cost sensitivity analysis for different MC-OXCs. The results show that the proposed architecture guarantees strictly nonblocking with lower costs. © 2008 SPIE.

关键词： Multicasting

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key technologies based on injection locked lasers for millimeter waveband radio over fiber access networks

Key technologies based on injection locked lasers for millim...

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International Nano-Optoelectronics Workshop (i-NOW)

作者： Zhangyuan Chen Weiwei Hu Cheng Hong Cheng Zhang Mingjing Li Yushu Chen Xiang Wang State Key Laboratory of Advanced Optical Communication Systems & Networks Electronics Department Peking University Beijing China

Some enabling technologies based on injection locked lasers for millimetre waveband radio over fiber access networks are discussed, including optical millimeter wave generation, single-band modulation, wavelength reus... 详细信息

关键词： optical fiber communication optical fiber networks optical modulation Millimeter wave technology Millimeter wave communication optical signal processing optical fibers

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Design of 25-inch Direct Illumination-type LED Backlight

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Semiconductor Photonics and Technology 2008年第3期14卷 143-146,195页

作者： LIANG Bao-wen LI Rong-yu GUO Ying-ying WANG Shuai CHEN Xiu-jin State Key Laboratory of Local Fiber-optic Communication Networks and Advanced Optical Communication Systems Department of Electronic Engineering Shanghai Jiaotong University Shanghai 200240 CHN

We utilized "direct illumination-type" LED backlight project, made white-light LED array in rectangle, designed a sheet of reflective film, a sheet of diffuser and two sheets of brightness enhancement film, then analyzed illuminance chart which was the result of simulation in several distance between reflective film and optical film. It showed the best matching between illuminance and uniformity while in 25mm distance. Finally, we discussed some problems with thermal dispersion.

关键词： backlight LED direct uniformity

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Data segments aggregation performance in next generation avionics systems

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Guangxue Xuebao/Acta Optica Sinica 2008年第SUPPL. 2期28卷 253-257页

作者： Huang, Hui He, Hao Jin, Yaohui Huang, Haoyi Wu, Jianmin State Key Laboratory on Advanced Communication Systems and Networks Shanghai Jiaotong University Shanghai 200240 China National Defense Science and Technology Key Laboratory for Avionics System Integration Technology Shanghai 200233 China

We integrate the advantages of optical packet switching (OPS) network and fibre channel (FC) technology, and put forward fibre channel transportation based on optical packet switching network (FC over OPS) as a solution for next generation avionics systems internetworking. We focus our research work on the interrelation between data segments aggregation and network real-timing performance. By simulation, we analyze the impact that bandwidth, minimum efficiency threshold and timing contribute to the network real-timing. Furthermore, we complete hardware prototype design and simulation, compare the results between software and hardware simulation and analyze the performance of this algorithm.

关键词： Packet switching

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Achieving both high precision and high recall in near-duplicate detection

Achieving both high precision and high recall in near-duplic...

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17th ACM Conference on Information and Knowledge Management, CIKM'08

作者： Huang, Lian'en Wang, Lei Li, Xiaoming Institute of Network Computing and Distributed Systems Peking University Beijing 100871 China Shenzhen Graduate School of Peking University Shenzhen Guangdong 518055 China State Key Laboratory of Advanced Optical Communication Systems and Networks Peking University Beijing 100871 China

ISBN: (纸本)9781595939913

To find near-duplicate documents, fingerprint-based para-digms such as Broder's shingling and Charikar's simhash algorithms have been recognized as effective approaches and are considered the state-of-the-art. Nevertheless, we see two aspects of these approaches which may be improved. First, high score under these algorithms' similarity measurement implies high probability of similarity between documents, which is different from high similarity of the documents. But how similar two documents are is what we really need to know. Second, there has to be a tradeoff between hash-code length and hash-code multiplicity in fingerprint paradigms, which makes it hard to maintain a satisfactory recall level while improving precision. In this paper our contributions are two-folded. First, we propose a framework for implementing the longest common subsequence (LCS) as a similarity measurement in reason-able computing time, which leads to both high precision and recall. Second, we present an algorithm to get a trustable partition from the LCS to reduce the negative impact from templates used in web page design. A comprehensive exper-iment was conducted to evaluate our method in terms of its effectiveness, efficiency, and quality of result. More specifi-cally, the method has been successfully used to partition a set of 430 million web pages into 68 million subsets of simi-lar pages, which demonstrates its effectiveness. For quality, we compared our method with simhash and a Cosine-based method through a sampling process (Cosine is compared to LCS as an alternative similarity measurement). The result showed that our algorithm reached an overall precision of 0.95 while simhash was 0.71 and Cosine was 0.82. At the same time our method obtains 1.86 times as much recall as simhash and 1.56 times as much recall as Cosine. Compar-ison experiment was also done for documents in the same web sites. For that, our algorithm, simhash and Cosine find almost the same number of true-positives at

关键词： Websites

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A fast method for downlink cell search in TD-SCDMA

A fast method for downlink cell search in TD-SCDMA

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International Conference on communication systems

作者： Wei Jian Jianguo Yu Jianxin Wang Lin Wang Key Laboratory of Optical Communication and Light wave Technology (Ministry of Education) University of Posts슠and슠Telecommunications슠 Beijing China State Key Laboratory of Optical Communication Technologies Networks Wuhan China Key-Laboratory of All-Optical networks & Advanced Communications Networks Beijing Jiaotong University Beijing China

TD-SCDMA cell search is performed in three scenarios: downlink guide slot (DwPTs) position search, downlink synchronization code (SYNC_DL) position search and frame synchronization control. A fast method for every scenarios of downlink cell search in TD-SCDMA is proposed. Based on characteristics of frame and slot structure in TD-SCDMA, power-matching stencil method is used to find the position of downlink guide slot (DwPTs) and definition stencil method is proposed to decide the position of downlink synchronization code (SYNC_DL). Moreover, the problem of channel estimation for TD-SCDMA mobile communication system is investigated and a new fast method for detecting downlink guide channel is derived to control frame synchronization. This new method simplifies calculation complexity, realizes fast and high efficiency network test system and can be applied to TD-SCDMA network planning and optimization. The conclusion can be proved by simulations and field testing which are mentioned.

关键词： Downlink Time division synchronous code division multiple access Frequency synchronization Laboratories optical fiber communication Educational technology communication system control Channel estimation Multiaccess communication Finite impulse response filter

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A two-stage metro-access integrated network enabling all-optical virtual private network

A two-stage metro-access integrated network enabling all-opt...

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European Conference on optical communication (ECOC)

作者： Yue Tian Qingjiang Chang Yikai Su Department of Electronic Engineering State Key Laboratory of Advanced Optical Communication Systems and Networks Shanghai Jiaotong University Shanghai China

We present a two-stage TDM/WDM metro-access integrated network with all-optical VPN across different sub-PONs. This feeder-ring with access-trees based architecture is employed to provide VPN service covering a wider ... 详细信息

关键词： Virtual private networks optical network units Differential quadrature phase shift keying WDM networks Wavelength division multiplexing Arrayed waveguide gratings Passive optical networks Time division multiplexing optical interferometry optical modulation

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Simultaneous Transmission of Point-to-Point Data and Selective Delivery of Video Services in a WDM-PON Using ASK/SCM Modulation Format

Simultaneous Transmission of Point-to-Point Data and Selecti...

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optical Fiber communication (OFC) Conference

作者： Qingjiang Chang Junming Gao Qiang Li Yikai Su State Key Laboratory of Advanced Optical Communication Systems and Networks Department of Electronic Engineering Shanghai Jiaotong University Shanghai China

We propose and experimentally demonstrate simultaneous transmission of point-to- point data signals and selective delivery of point-to-multipoint video services based on extinction ratio control of ASK data and subseq... 详细信息

ISBN: (纸本)9781557528599

关键词： Amplitude shift keying optical network units optical transmitters Erbium optical modulation Passive optical networks Downlink Multimedia communication Broadcasting optical receivers

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